November is kind of a dry season (less rain) (weather is almost the same all year long, sometimes it rains more, thats it).

Security: best in years, just don't be too bold and stay on the main roads, cities or parks and everyting will be ok.

I made a road trip to the north coast from Bogota 3 months ago (1000 + miles), not a problem; I went to the desert on the far north (guajira, great for windsurf) to the tayrona park (surf and scuba diving) (very little kayaking but it must be a great place for it).

Where are you planning to go? (coast, mountains, amazon jungle or plains?).
Are you into xtreme sports? you can do all kind of sports here, surf and scuba on the caribean or the pacific, kayak, rafting, parasailing, trekking, rock climbing, you name it.